Amanda Knox says contemplated suicide in Italian prison

Amanda Knox (R) cries and gestures to friends while her mother Edda Mellas sits next to her during a news conference at Sea-Tac International Airport, Washington after Knox landed there on a flight from Italy, October 4, 2011.

Reuters/Anthony Bolante

American Amanda Knox said she considered suicide if her 2007 murder conviction of a British roommate in Italy had not been overturned, according to an advance copy of Knox's forthcoming memoir.

In her memoir, excerpts of which were obtained by ABC Television News and released on Thursday, Knox said she "imagined myself a corpse" while in prison and began considering killing herself if her sentence was increased to life in prison from her initial 26-year sentence.

"I started to understand how you could feel so locked inside your own life that you could be so desperate to escape, even if it meant that you would no longer exist," Knox writes in "Waiting to Be Heard."

The memoir will be published by HarperCollins on April 30 in conjunction with an interview with ABC's Diane Sawyer that is due to air the same day.

Knox, 25, spent four years in prison for the murder of Meredith Kercher while both were exchange students at Perugia University in Italy. Knox was acquitted on appeal in 2011 and she returned to her Seattle-area home, but Italy's high court last month ordered a retrial.

She lists many ways to kill oneself in prison, including poisoning with bleach, swallowing shards of glass or a broken pen, hanging and hitting your head against a wall.

"Less effective but, I thought, more dignified was bleeding yourself to death," Knox writes. "I imagined it would be possible to get away with enough time in the shower."

Knox, who became a tabloid sensation in Britain and Italy, writes in the memoir that her cell mates were crude and hostile to her and thought her a snob because she would read and write to pass the time.

Knox also reveals that if she would have had to serve her initial 26-year sentence that she would have considered adopting a child on her release.

Kercher's half-naked body, with more than 40 wounds and a deep gash in the throat, was found in the apartment she shared with Knox in the university town in central Italy.

The Italian high court in March also overturned the acquittal of Knox's former boyfriend Raffaele Sollecito and ordered a new trial on a date still to be set.

The acquittal came after independent forensic experts said the police scientific evidence was deeply flawed and the investigation had been bungled.

Knox's memoir covers her time in Italy up until her release from prison.

In a separate interview with People magazine, due to be published on April 26, Knox said she was still haunted by her ordeal.

"Things creep up on me and all of a sudden I'm overwhelmed by the feeling of helplessness and that desperation and fear to even hope," she told People. "Just that can make my heart race and makes me paralyzed until I can breathe it away."

ABC is part of Walt Disney Co and HarperCollins is owned by News Corp.